1. Field of the Invention
The present invention relates to a optical switching method of an optical packet switching equipment, and more particularly, to a method capable of optical packet switching even in a case where physical optical data in an optical packet switch has not the shape of a packet but the shape of continuous data, and a system therefor.
2. Description of the Related Art
As shown in FIG. 1, an optical packet switching equipment recognizes the header information of optical packets input into optical packet header recognizers 1011 and 1012 at each of input terminals, extracts information related to output terminals of corresponding optical packets and packet synchronization information from the header information of the optical packets, transmits the information to an optical packet switch controller 104. The optical packet switch controller 104 synthesizes the information from the optical packet header recognizers 1011 and 1012 at each of input terminals, gives commands to optical packet synchronizers 1021 and 1022, aligns input optical packets, gives commands to optical packet collision eliminators 1031 and 1032. In a case where there are optical packets to be output to the same output terminal, the optical packet switch controller 104 gives commands to optical packet collision eliminators 1031 and 1032, adjusts the optical packets so that the optical packets don't collide with one another by using a proper method, gives control commands to an optical switch 105 so that each of the optical packets is switched into a desired output terminal.
In general, as shown inn FIG. 2, a optical switching method of an optical packet switching equipment includes a method for setting up an optical path corresponding to only when there are optical packets. That is, in step 201, it is determined whether optical packets are inputted into input terminals of the optical packet switch. In step 202, when the optical packets are inputted into the input terminals of the optical packet switch, the optical packets are switched into destination output terminals of the optical packets during the lengths of the optical packets. In step 203, the optical packets are not switched to any output terminals of the optical packet switch when the optical packets are not inputted into the input terminals of the optical packet switch. The optical switch is simply controlled by the method but physical data inputted into the optical packet switch must have a packet shape, and when there are no optical packets, it is recognized that there are no optical signals themselves. That is, when there are no optical packets but optical signals, an optical path cannot be set up, and thus the shape of the optical signals cannot be maintained to output terminals.
Hereinafter, the above-mentioned conventional switching method will be lo describe with reference to FIG. 3. FIG. 3 illustrates examples of an optical switch, optical signals inputted into input terminals of the optical switch, and optical signals outputted to output terminals of the optical switch with time shown on the horizontal axis. Right oblique-lined packets among the optical signals at the input terminals direct a first output terminal, horizontal-lined packets direct a second output terminal, and left oblique-lined packets direct a third output terminal, and numbers in each packet represent the number of the input terminals. Blank data between the packets are arbitrary dummy data interposed between the packets and represent the number of the input terminals as figures. The optical signals at the output terminals illustrate the result in which only the optical packets among the optical signals at the input terminals are switched into the output terminals. Here, dummy data mean arbitrarily added data so as to make the optical signals including the optical packets as continuous signals, for example, signals '01010101 . . . in which ‘0’ and ‘1’ are repeatedly represented.
For this reason, in order to implement an optical packet switch by the conventional optical switching method of an optical switch, a burst mode optical transmitter-receiver for transmitting and receiving optical data having the shape of a packet is necessary. However, since a conventional burst mode optical transmitter-receiver at the speed of 155 Mbps is used commonly, it is very difficult to implement a high-speed burst mode optical transmitter-receiver required for an optical packet switch.